Where a mobile phone has been reported to a mobile network operator as stolen or missing, future access to that network (and potentially to other networks, where there is an agreement to share such information) can be prevented. To do this, a database, often part of the home location register (HLR) in the core network, is deployed. Access is denied, allowed or restricted to any given mobile phone depending upon the entry for that phone, if any, within that database. Such databases are generally referred to as equipment identity registers (EIR).
EIRs are typically arranged to hold records for three classes of mobile terminal; the classes are conventionally termed “black”, “grey” and “white”.
When a mobile requests services from the network, the signaling required to set up the required connection includes a message from the equipment containing a unique equipment identifier such as the IMEI (International Mobile Equipment Identity).
It is the IMEI that is stored in the relevant category of the EIR. Thus, in establishing a service, the IMEI may be checked against the EIR, to assess which equipment category the mobile phone falls into. A “black” device is one that has been reported stolen or whose operation on the network is otherwise determined to be undesirable for the network operator (for instance it may be unauthorized or in some way defective: it would be detrimental for network operation to allow a device that has malfunctioning power control). Black-listed mobiles will denied access to the network.
By contrast, grey mobiles would generally be allowed to use the network but they may be treated differently (their attempts to access the network might be logged and stored in a log file).
As might be expected, “white” mobiles are those that comply with network operator requirements.
Conventional EIRs are thus designed to blacklist individual stolen handsets. Blacklisting whole classes of devices (for example counterfeit, defective batch etc.) or specific terminals using compromised or undesirable versions of software (particularly operating system software) is not trivial and may be impractical.
Furthermore, EIRs are ineffective when the handset connects over non-mobile networks, or to networks which don't have EIRs, or don't have the IMEI on their black-list.
It has also been possible to work around black-listing by altering the IMEI carried by the equipment.
In some extreme cases, badly built terminals have the potential to damage the mobile telecommunications networks even before an IMEI is presented.
It is therefore an object of the invention to obviate or at least mitigate the aforementioned problems.